Methods for estimating synonymous and nonsynonymous substitution rates among protein-coding sequences adopt different mutation (substitution) models with subtle yet significant differences, which lead to different est...Methods for estimating synonymous and nonsynonymous substitution rates among protein-coding sequences adopt different mutation (substitution) models with subtle yet significant differences, which lead to different estimates of evolutionary information. Little attention has been devoted to the comparison of methods for obtaining reliable estimates since the amount of sequence variations within targeted datasets is always unpredictable. To our knowledge, there is little information available in literature about evaluation of these different methods. In this study, we compared six widely used methods and provided with evaluation results using simulated sequences. The results indicate that incorporating sequence features (such as transition/transversion bias and nucleotide/codon frequency bias) into methods could yield better performance. We recommend that conclusions related to or derived from Ka and Ks analyses should not be readily drawn only according to results from one method.展开更多
We present a ballistocardiogram(BCG)measurement system for obtaining the BCG signal.The performance of the BCG measurement system was tested,including the dynamic response frequency of the platform(32 Hz with a 75 kg ...We present a ballistocardiogram(BCG)measurement system for obtaining the BCG signal.The performance of the BCG measurement system was tested,including the dynamic response frequency of the platform(32 Hz with a 75 kg load),and the signal to noise ratio of the system(minimum 23 dB).Factors that could influence BCG recording during measurement were investigated by collecting data from 48 healthy subjects(28 males and 20females).The basic features of the BCG signal,such as the amplitude and time interval,were extracted,and differences by gender were analyzed.A correlation between the IJ amplitude(amplitude difference between I-and J-peak)and the respiration phase was found(R2=0.49).The BCG signals for both sitting(SiBCG)and standing(StBCG)postures were obtained using this system.These showed that the StBCG amplitudes were larger than those of SiBCG but there was no significant difference in the time intervals.The robustness of our system was verified,and its potential for non-invasive cardiac activity monitoring was demonstrated.展开更多
基金This work was supported by the Ministry of Science and Technology of China(Grant No.2001AA231061)the National Natural Science Foundation of China(Grant No.30270748)awarded to JY.We thank Mr.Jun Li for valuable discussion.
文摘Methods for estimating synonymous and nonsynonymous substitution rates among protein-coding sequences adopt different mutation (substitution) models with subtle yet significant differences, which lead to different estimates of evolutionary information. Little attention has been devoted to the comparison of methods for obtaining reliable estimates since the amount of sequence variations within targeted datasets is always unpredictable. To our knowledge, there is little information available in literature about evaluation of these different methods. In this study, we compared six widely used methods and provided with evaluation results using simulated sequences. The results indicate that incorporating sequence features (such as transition/transversion bias and nucleotide/codon frequency bias) into methods could yield better performance. We recommend that conclusions related to or derived from Ka and Ks analyses should not be readily drawn only according to results from one method.
基金supported by the National Natural Science Foundation of C@hina (810701750)
文摘We present a ballistocardiogram(BCG)measurement system for obtaining the BCG signal.The performance of the BCG measurement system was tested,including the dynamic response frequency of the platform(32 Hz with a 75 kg load),and the signal to noise ratio of the system(minimum 23 dB).Factors that could influence BCG recording during measurement were investigated by collecting data from 48 healthy subjects(28 males and 20females).The basic features of the BCG signal,such as the amplitude and time interval,were extracted,and differences by gender were analyzed.A correlation between the IJ amplitude(amplitude difference between I-and J-peak)and the respiration phase was found(R2=0.49).The BCG signals for both sitting(SiBCG)and standing(StBCG)postures were obtained using this system.These showed that the StBCG amplitudes were larger than those of SiBCG but there was no significant difference in the time intervals.The robustness of our system was verified,and its potential for non-invasive cardiac activity monitoring was demonstrated.
